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NSW GUIDELINES FOR

GREYWATER REUSE IN SEWERED, SINGLE HOUSEHOLD RESIDENTIAL PREMISES

// MAY 2008

Printed on FSC mixed source paper containing 80% recycled fibre, ISO 14001.

Department of Energy, Utilities and Sustainability Level 17, 227 Elizabeth Street, SYDNEY NSW 2000

GPO Box 3889, SYDNEY NSW 2001 Tel: 02 8281 7777 Fax: 02 8281 7799 Web: www.dwe.nsw.gov.au Email: [email protected]

© State of NSW through the Department of Water and Energy 2008 ISBN number 978 0 7347 5940 5 DWE 08_092 May 2008

This work may be freely reproduced and distributed for most purposes, however some restrictions apply. Contact the Department of Water and Energy for copyright information.

ACKNOWLEDGEMENTSThis guideline was prepared with consideration of feedback from a wide range of NSW government departments, local councils, industry and other relevant stakeholders who provided comment during public consultation on the draft guideline.

A number of information sources were referenced during the development of the guideline. A comprehensive list is appended to this document.

Disclaimer: While the Department of Water and Energy has taken due care in the preparation of these guidelines including the appendices, it accepts no liability for any errors or omissions, nor for any use of the guidelines by any person.

1

PART A – INTRODUCTION 3

1 Introduction 4

1.1 Overview 4

1.2 Why Use Greywater? 4

1.3 What Type of System Should be Used? 4

1.4 Structure of this Document 5

2 Greywater Characteristics 5

2.1 Definitions 5

2.2 Where Does Greywater Come From? 5

2.3 Water Usage Volumes 6

2.4 Composition of Greywater 7

2.4.1 Microbiological Quality 7

2.4.2 Chemical and Physical Quality 7

Nutrients 7

Salts 8

PART B – GREYWATER DIVERSION DEVICES 9

3 Greywater Diversion Devices 10

3.1 Overview 10

3.2 Conditions of Approval 10

3.3 Using Greywater Safely 11

3.4 Greywater Reuse Estimations 13

3.5 Choosing a Greywater Diversion Device 14

3.6 Sub-surface Irrigation 14

3.7 Marking, Labelling and Signage 14

3.8 Maintenance 15

3.9 Responsibilities 16

3.10 Offences and Penalties 16

NSW GUIDELINES FOR GREYWATER REUSE IN SEWERED, SINGLE HOUSEHOLD RESIDENTIAL PREMISES //

2 // NSW DEPARTMENT OF WATER AND ENERGY

PART C – ADVISORY INFORMATION ON THE REUSE OF GREYWATER 17

4 Greywater Treatment Systems 17

4.1 Overview 17

4.2 Accreditation 17

4.3 Approvals 17


4.5 Greywater Reuse Estimations 20

4.6 Marking, Labelling and Signage 20

4.7 Irrigation 20

4.8 Maintenance 20

4.9 Responsibilities 21

4.10 Offences and Penalties 21

5 Manual Bucketing of Greywater 22

5.1 Overview 22

5.2 Conditions of Approval 22


Glossary of Terms 24

References 26

Bibliography 26

Appendix A – Greywater Decision Flow Charts 28

Appendix B – Greywater Reuse Estimations 31

B1 Potential for Reuse 31

B2 Greywater Generation 33

B3 Water Balance 36

Appendix C – Management of Greywater 39

C1 Risk Management Approach 39

C2 Hazard Identification 40

C3 Risk Assessment 40

C4 Best Practice Management Controls 42

Pathogens 42

Nutrients 44

Salts 45

Chemicals 46

Physical Contaminants 46

Water Volume 47

Appendix D – Fact Sheets 49

PART AINTRODUCTION

Section 1 – Introduction

Section 2 – Greywater Characteristics

// NSW DEPARTMENT OF WATER AND ENERGY4

1 INTRODUCTION

1.1 Overview

These guidelines provide direction on the use of greywater diversion devices (GDDs) in single households, and have been developed to specify the conditions for exemption from prior approval by councils for greywater diversion. The Local Government (General) Amendment (Domestic Greywater Diversion) Regulation 2006 allows an exemption from prior approval by councils if certain practices are implemented and conditions are met. The main purpose of these guidelines is to provide guidance on meeting those practices and conditions (Part B of this document).

The secondary purpose of the guidelines is to provide additional advisory information to the owners and/or occupiers of sewered residential premises on greywater treatment systems and manual bucketing of greywater. This information is contained in Part C of this document.

Part C also contains guidance on the use of greywater treatment systems (GTSs). However, it is important to note that greywater treatment systems continue to require prior approval from the relevant local government authority for installation, and operation of the system (Item C6, Section 68, Local Government Act 1993). There are no exemptions from this requirement. A council must not approve the installation of a GTS unless the system has been accredited by the NSW Department of Health (Clause 41(1) of the Local Government (General) Regulation 2005).

These guidelines do not provide detailed information on the responsibilities of plumbers, installers or manufacturers of systems. Specific local, state and federal requirements exist for plumbers, installers and manufacturers of systems, including the NSW Plumbing Code of Practice and the Trade Practices Act that should be considered as primary sources of information.

These guidelines provide comprehensive information for the reuse of greywater on residential premises in sewered areas of NSW. These guidelines replace the NSW Health document ‘Greywater Reuse in Sewered Single Domestic Premises’ (April 2000).

This document has been prepared by the Department of Water and Energy (DWE) on behalf of the NSW Government with input from other agencies, including the Department of Health, Department of Local Government and Sydney Water.

1.2 Why Use Greywater?

Recent widespread drought in Australia, combined with the continued growth of cities and the need to provide for environmental flows in our river systems, has resulted in increasing pressure on drinking water supplies in most large cities and many regional areas of Australia.

Greywater from residential premises (single households) is a resource and can be reused on-site for garden and lawn irrigation or, if treated appropriately, for toilet flushing and laundry use (washing machine only). Substituting greywater for drinking water for these end uses will not only reduce the demand on drinking water supplies, but will also reduce the amount of wastewater discharged to the environment.

1.3 What Type of System Should be Used?

There are three ways of reusing greywater that can be implemented for sewered residential premises in NSW:

greywater diversion, which diverts greywater generated by a premises to the garden or lawn for use in sub-surface irrigation;

greywater treatment, which treats greywater for other reuse, such as toilet flushing, washing machine and surface irrigation; and

manual bucketing, which involves the reuse of relatively small quantities of greywater for irrigation.

5NSW GUIDELINES FOR GREYWATER REUSE IN SEWERED, SINGLE HOUSEHOLD RESIDENTIAL PREMISES //

1.4 Structure of this Document

An overview of the structure of this document is provided in order to direct readers to the section of the guidelines most appropriate to their needs:

Part A – Introduction

Section 1 – Introduction an overview of the purpose of the document and its application, relevant to all readers.

Section 2 – Greywater Characteristics, relevant to all readers.

Part B – Compliance with this part is necessary to obtain an exemption for prior approval for greywater diversion devices

Section 3 – Greywater Diversion Devices, conditions for meeting the exemption criteria.

Part C – Advisory information on the reuse of greywater

Section 4 – Greywater Treatment Systems.

Section 5 – Manual Bucketing of Greywater.

Appendix A – Greywater decision flow charts

Appendix B – Greywater reuse estimations

Appendix C – Best practice management controls

Appendix D – Greywater fact sheets

2 GREYWATER CHARACTERISTICS

2.1 Definitions

Greywater: For the purpose of these guidelines, greywater means wastewater from washing machines, laundry tubs, showers, hand basins and baths where a greywater diversion device or manual bucketing is used. It does not include wastewater from a kitchen, toilet, urinal or bidet.

For the purpose of these guidelines, it also means wastewater from washing machines, laundry tubs, showers, hand basins, baths and kitchens where a greywater treatment system is used. It does not include wastewater from a toilet, urinal or bidet.

Residential Premises: Refers to a single, detached household residential premises. It does not include premises comprising more than one dwelling.

2.2 Where Does Greywater Come From?

Greywater is generated by every residential household that is occupied, and can be reused to provide a reliable source of water for those uses that do not require drinking water (including irrigation, toilet flushing and washing machine use).

The characteristics of greywater produced by a household will vary according to the number, age, lifestyle, health status and water usage patterns of the occupants.

There are essentially two different greywater streams:

1. Bathroom greywater (bath, basin, and shower) – contributes about 59 per cent of the total usable greywater volume in a typical household (Loh & Coghlan, 2003). Bathroom greywater can be contaminated with hair, soaps, shampoos, hair dyes, toothpaste, lint, nutrients, body fats, oils and cleaning products. It may also contain some faecal contamination (and the associated pathogens) through body washing.


2. Laundry greywater – contributes about 41 per cent of total usable greywater volume in a typical household (Loh & Coghlan, 2003). Wastewater from the laundry varies in quality from wash water to rinse water to second rinse water. Laundry greywater can be contaminated with lint, oils, greases, laundry detergents, chemicals, soaps, nutrients and other compounds. It may also contain some faecal contamination (and the associated pathogens) through washing contaminated clothes. Greywater generated from the laundry is often the easier source of greywater to access, although it is usually more contaminated than bathroom greywater (Jeppesen and Solley, 1994; Christova-Boal et al., 1996).

Kitchen wastewater is sometimes considered as a greywater stream; however, for the reuse of greywater by greywater diversion devices (GDDs) it is not appropriate to include kitchen wastewater due to the contaminants (food particles, oil and grease). Kitchen wastewater can be treated for reuse by greywater treatment systems (GTSs).

Under the NSW Code of Practice: Plumbing and Drainage 3rd Edition 2006, only greywater from the bathroom and laundry can be reused by GDDs. Greywater from the kitchen must not be reused by GDDs.

2.3 Water Usage Volumes

The average single sewered household in Sydney (based on 3 persons per household) uses (unrestricted) 825 litres of water each day, or approximately 300,000 litres (300 kilolitres) per year (Sydney Water, 2005). This equates to approximately 339 litres of greywater per house per day. Of this, 198 litres is from baths and showers, and 141 litres is from the laundry (Table 2.1) (Loh & Coghlan, 2003; Sydney Water, 2005). Approximately 223 litres each day is used outdoors for garden and lawn irrigation, car washing, swimming pools etc. (Sydney Water, 2005). By reusing greywater for irrigation a household has the potential to save between 50,000 and 100,000 litres of drinking water per year.

Table 2.1: Per Capita In-house Usage (Loh and Coghlan, 2003)

ApplianceResidential Premise (Single Household)

L/house/day* L/person/day

Bath and shower 198 66

Washing machine 141 47

Sub-total Greywater 339 113

Toilet 124 41

Taps (includes kitchen) 140 47

Total in-house 603 201

* Based on 3 people per house.

Water usage will vary according to the practice of each household. Approximate percentages of water use volumes for in-house use are provided in Figure 2.1.

Figure 2.1: Proportion of In-house Usage Available for Reuse (Loh & Coghlan, 2003)

Washing machine

24%

Bath and shower 33%Toilet 20%

Taps (including kitchen)

23%

Greywater – Available for reuse covered by these guidelines

Blackwater – Not available for reuse, not covered by these guidelines

Greywater – Not available for reuse, by greywater diversion devices


2.4 Composition of Greywater

2.4.1 Microbiological Quality

The thermotolerant coliform group of bacteria are used as an indicator of microbiological quality. Thermotolerant coliforms are also known as faecal coliforms and are a type of micro-organism which typically grow in the intestine of warm-blooded animals (including humans) and are shed in their millions in each gram of faeces. Occurrence of faecal coliform bacteria in water indicates a risk of human illness or infection through contact with the water.

In general, the number of faecal coliforms in greywater is low unless greywater is generated from washing nappies or clothes contaminated with faeces or vomit (Jeppesen and Solley, 1994). This suggests that the numbers of harmful pathogens are also low.

2.4.2 Chemical and Physical Quality

There is a high amount of variability in the chemical and physical quality of greywater produced by any household, due to factors such as the source of water, the water use efficiency of appliances and fixtures, individual habits, products used (e.g. detergents, shampoos, soaps etc.) and other site-specific characteristics.

The amount of salt (sodium, calcium, magnesium, potassium and other salt compounds), oils, greases, fats, nutrients and chemicals in greywater can largely be managed by the types of products used within a household. The Dos and Don’ts in Sections 3, 4 and 5 provide guidance on how to manage the chemical and physical quality of greywater. Appendix C also goes into further detail on the risks of using greywater and how to best manage these risks.

Nutrients

Phosphorus and nitrogen are nutrients necessary for plant growth. Greywater, containing nutrients generated from the bathroom and laundry, may be substituted for fertiliser to provide phosphorus and nitrogen to the garden and lawn.

Table 2.2 shows the estimated amount of nutrients contained in greywater reused on a one square metre irrigation area of a residential household over a one year period, compared with the amount of nutrients applied by following recommended dosage rates over a one year period provided by manufacturers of typical lawn fertilisers.

Table 2.2: Nutrient Application Resulting from Greywater Reuse

NutrientBathroom Greywater Laundry Greywater Fertiliser

Range (grams/year/m2) Range (grams/year/m2) Average (grams/year/m2)

Total Nitrogen (N) 3.22 – 24.0 0.7 – 48.0 17.6

Total Phosphorus (P) 0.08 – 2.16 0.04 – 50.4 11.3

Source: Based on the composition of five readily available lawn fertilisers – Brunnings, Hortico, Munns, Shirley’s and Yates and greywater composition data from Christova-Boal et al. (1996).


Excessive nutrient loads should be avoided to prevent damage to soil, plants, groundwater and off-site waterways. However, it is apparent from Table 2.2 that the typical nutrient loads that are applied to the soil by irrigating with greywater are similar to those that are applied by following the directions on common fertiliser packages. The upper limits of ranges can be managed by the selection of appropriate laundry detergents (and similar products) that are low in nitrogen and phosphorus. The reuse of greywater, therefore, has the potential to significantly reduce the need for fertiliser application on gardens and lawns. The application of nutrients through the irrigation process is also preferred, as the nutrients will be applied more gradually and will reduce the risk of nutrients being washed away during rain events.

The variability in the nutrient loadings is influenced by the use of different washing detergents, personal hygiene products (soaps, shampoos), and cleaning agents. The amount of nutrients in the products being used by the household has a direct relationship with the amount of nutrients that are present in the greywater when it is reused for irrigation. By managing the type and amount of washing detergents, personal hygiene products and cleaning agents that are used, the amount of nutrients in greywater can be managed.

Further information regarding the management of nutrients in greywater and managing vegetation that is irrigated by greywater can be found in Appendix C and in the Greywater Fact Sheets.

Salts

Salts in greywater originate from washing detergents and are commonly in the form of sodium, magnesium and calcium compounds (Patterson, 2006).

The application of greywater to land introduces to the soil quantities of many salts that cannot be drained from the root zone under normal rainfall. Increases in salt concentration in soil will depend upon the unique combination of soil type, greywater composition and drainage (Patterson, 2006).

The major risks of salts contained in greywater are the accumulation of salts in the soil structure leading to a loss of soil permeability (ability to absorb water) which can cause degradation to vegetation. Sodium salts are always very soluble, many times more soluble than calcium or magnesium salts, and soil sodicity (soil degradation due to sodium salts) presents particular problems to soil and vegetation, including soil permeability and plant growth (Patterson, 2006).

The salts originate from washing detergents, which vary in their salt content. Reducing the quantity of salts, particularly sodium, is the most effective method to reduce the risk to soil and vegetation due to salts, and especially soil sodicity. Generally, powdered detergents contain the most salt as it is used in washing powders as filler. Concentrated powders generally contain less salt than normal powdered detergents, and liquid detergents contain the least salt of all washing detergents (Table 2.3).

Table 2.3: Sodium Adsorption Ratio (Patterson, 2006)

Greywater TypeSodium Adsorption Ratio (SAR)

Min Mean Max

Laundry (powder detergents)

1.2 9.2 52.1

Laundry (liquid detergents)

0.02 1 4

The sodium adsorption ratio (SAR) measures the relationship of the concentration of sodium cations (positive ions) in the water compared to the concentration of other cations in the water. Water with a SAR of greater than 6 is likely to raise the risk of sodicity in non-sodic soils, whilst a SAR of less than 3 may lower that risk in sodic soils. Table 2.3 clearly shows that if liquid detergents are used, greywater has a SAR with a maximum of 4, well within the acceptable SAR. Thus using liquid detergents instead of powder detergents will generally result in greywater with a reduced risk of causing soil degradation.

In addition to choosing washing detergents that are low in salts, and in particular sodium salts, there are other ways of managing a household’s soil to reduce the risks caused by salt application. These include incorporating organic matter into the soil by mulching, and the addition of lime or gypsum to already sodic soils.

PART BGREYWATER DIVERSION DEVICES

Section 3

Greywater Diversion Devices - Recommended Conditions for Gaining Exemption

Compliance with this Part will assist in satisfying the conditions for an exemption from prior approval for greywater diversion devices.


3 GREYWATER DIVERSION DEVICES

This section outlines the guidelines specifically pertaining to the use of greywater diversion devices at residential premises in sewered areas of NSW.

Compliance with this section will assist in satisfying the conditions for an exemption from prior approval for the operation of greywater diversion devices.

3.1 Overview

A greywater diversion device (GDD) is a hand-activated switch that diverts untreated greywater by gravity or pump directly to a sub-surface irrigation system.

A diversion system incorporates the following features:

a hand-activated valve

a switch or tap which is fitted to the outlet of the waste pipe of the plumbing fixture (e.g. a washing machine)

a coarse filter for screening out solids and oils/greases

non-storage surge attenuation

an overflow device

a garden irrigation or distribution system.

Greywater from a diversion device is untreated and must only be reused for sub-surface irrigation.

Greywater diversion is for the productive reuse, not easy disposal, of wastewater. It is important for owners and residents to recognise that a diverter must be treated as a garden tap. The diverter should only be turned on when the garden needs watering, at all other times it must be turned off. If the diverter is turned on all the time, over-watering has the potential to significantly damage plants and soil as well as increase the risk to residents’ health. Any greywater that can not be immediately reused for sub-surface irrigation at the residential premises must be diverted to sewer.

Reuse of greywater through a GDD at a residential household is considered to be a low risk activity if the requirements of these guidelines are met. By reusing only greywater produced within the household for sub-surface irrigation, the health risks associated with pathogen exposure are reduced, since those residing in the house are likely to have been exposed to the majority of the pathogens in the greywater, through contact with the other residents at the household. The main form of exposure for pathogens is through personal contact.

The reuse of greywater by a GDD where more than one dwelling is located on a block, including groups of town houses, villas and multi-unit dwellings, is not permitted. This is due to the fact that other residences will not have been exposed to the pathogens through personal contact, therefore increasing the risk of spreading disease through the community. A town house occupant using only that residence greywater on the garden within the premises is permitted. Use on common property gardens is not permitted.

Appendix A outlines the process for choosing and installing a greywater diversion device.

3.2 Conditions of Approval

The Local Government (General) Regulation 2005 under the Local Government Act 1993 requires prior council approval of greywater diversion. However, under Clause 75A of the Regulation, greywater diversion at residential premises may be carried out without the prior approval of the council if:

it is carried out in accordance with the Plumbing and Drainage Code of Practice;

a sewage management facility is not installed on the premises concerned; and

certain performance standards related to health and the environment are met (see Appendix C).

To obtain exemption from obtaining council approval the following conditions should also be satisfied:

the proposed site for installation is not located in an area registered as environmentally sensitive. Areas registered as environmentally sensitive are listed on the Department of Water and Energy web site (www.dwe.nsw.gov.au);


wastewater is not diverted from kitchen or toilet plumbing;

greywater is not stored in any way, or treated other than primary screening or filtration;

a washing machine standpipe, or WaterMark licensed diversion device, delivers the greywater to a sub-surface irrigation system;

the standpipe or diversion device has a switching or selection facility so that greywater can be easily diverted back to sewer;

any diversion device connected to, or modifying, the existing plumbing system is a WaterMark licensed device (previously a Plumbing Safety licence), and must be installed by a licensed plumber;

any diversion other than by gravity is only via a licensed non-storage surge tank and pump system installed by a licensed plumber;

some form of non-storage surge attenuation is installed as part of the diversion system (non-storage surge attenuation can be in the form of a tank system, a mulch basin or similar);

the local water utility is notified in writing by the installing plumber that a greywater diversion device is in place;

the landowner complies with these guidelines and any others issued by the Director General of the Department of Water and Energy.

It is the responsibility of the household owners to engage a licensed plumber to install the GDD and associated non-storage surge attenuation.

It is the responsibility of the installing licensed plumber to install the GDD and non-storage surge attenuation to meet the requirements of the NSW Code of Practice: Plumbing and Drainage 3rd Edition 2006. The plumber must ensure that controls to prevent the incidence of cross connection are implemented and that the local water utility is notified in writing that a diversion device is in place at the household. Written confirmation shall be in the form of a certificate of compliance and “as completed plans” (e.g. an amended sewer service diagram) or other documentation as required by the local water utility.

Where a GDD is to be installed at a residence, the property owner should check with their local water utility, prior to installation, that their property is serviced by a meter with an integral dual check valve to ensure backflow protection of the water supply.

The sub-surface irrigation system connected to the GDD does not require installation by a licensed plumber, but must meet the requirements of Section 3.6 and 3.7 and the performance standards in Clause 75A of the Local Government Regulation (reproduced in Appendix C of this Guideline). Also, where relevant, the installation of the sub-surface irrigation system must follow the manufacturer’s recommendations or design.

A GDD, unlike a GTS, does not require approval to operate the system.

3.3 Using Greywater Safely

It is important that greywater diversion is undertaken sensibly to ensure that public health and the environment are protected at all times. The control measures, presented in a list of ‘Dos and Don’ts’, have been compiled to provide owners and residents with a guideline of how to best manage their reuse of greywater. The list will assist owners to ensure that the reuse of greywater achieves the performance standards required for exemption from the prior approval of council. Each of these control measures is explained in further detail in Appendix C of these guidelines.

The control measures (Dos and Don’ts) for the GDD reduce the risks associated with reuse, whilst providing a water source that has the potential to improve the health and appearance of soil and plants at the household.


When undertaking diversion of greywater, DO:

DO check with the DWE web site (www.dwe.nsw.gov.au) to make sure your property is not registered in an area that is deemed to be environmentally sensitive.

DO install a greywater diversion device that has a WaterMark licence (previously a Plumbing Safety licence) and is listed by NSW Health.

DO reuse diverted untreated greywater only for sub-surface irrigation (at least 100 mm below the surface of soil or mulch).

DO ensure the greywater diversion device is switched back after irrigation periods so that greywater is diverted to sewer.

DO undertake a water balance (refer to Appendix B3) to estimate the amount of water that can be reused by the household.

DO select garden-friendly detergents that are biodegradable and low in phosphorus, sodium, boron and chloride.

DO select washing detergents that are low in salt – consider using a powder concentrate, or a liquid washing detergent (refer to fact sheets for further information).

DO monitor plant and soil response to greywater irrigation.

DO occasionally irrigate with drinking water to disperse salts from the soil (only necessary during extended periods of zero rainfall).

DO consider applying a soil rewetting agent every six months.

DO use a filter to screen solids when using a diversion device.

DO ensure that regular maintenance is undertaken, including cleaning out the greywater diversion device filter weekly and maintaining the sub-surface irrigation system.

DO mark and label all pipes and use signs to indicate greywater reuse (refer to Section 3.7).

When undertaking diversion of greywater, DON’T:

DON’T leave a diversion device on all the time. Treat it like a garden tap and only reuse greywater when the garden needs watering. Greywater is for reuse, not disposal.

DON’T reuse toilet or kitchen wastewater.

DON’T reuse greywater during rain.

DON’T reuse greywater from the washing of nappies or contaminated clothing.

DON’T reuse greywater when a resident is sick, e.g. has diarrhoea.

DON’T reuse greywater generated by cleaning in the laundry or bathroom, or when using hair dye or other chemicals.

DON’T reuse greywater generated by washing rags used for painting or for maintaining machinery and vehicles.

DON’T reuse greywater to top up rainwater tanks or swimming pools.


DON’T store untreated greywater.

DON’T over-water.

DON’T reuse greywater on plants that will be eaten raw or where fruit has fallen to the ground and could be eaten.

DON’T use greywater to wash paths, driveways or cars.

DON’T allow direct contact or ingestion of the greywater.

DON’T use greywater to irrigate on dune sand or shallow rocky soil unless the soil has been enriched to a minimum 300mm in depth.

DON’T reuse greywater so that it flows into the streets or down stormwater drains.

DON’T install drippers of a sub-surface irrigation system within one metre of boundary lines, inground pools and inground potable water tanks and buildings.

DON’T let greywater go beyond the property boundary and cause a nuisance to neighbours.

DON’T use greywater in households where immuno-suppressed occupants are present.

3.4 Greywater Reuse Estimations

To estimate a household’s greywater requirements, a water balance can be undertaken to consider both the amount of greywater that has the potential to be reused, and the amount of greywater that can be generated to meet the needs of the household. This is important because a typical metropolitan household can potentially generate much more water than is needed for use on the garden.

All of the information and calculations to undertake a water balance are provided in Appendix B: Greywater Reuse Estimations. A water balance provides guidance for managing greywater to protect public health and the environment. It is essential that owners or residents complete the water balance in order to meet the conditions for exemption from council approval.


3.5 Choosing a Greywater Diversion Device

Greywater diversion devices (GDDs) are evaluated to the Australian Technical Specification ATS 5200.460-2005. Certification to the technical specification for plumbing and drainage products is obtained by the manufacturer by way of a WaterMark licence (previously a Plumbing Safety licence).

Diversion devices are only exempt from requiring approval from council if they are licensed with a WaterMark licence (previously a Plumbing Safety licence).

Figure 3.1: WaterMark Certification

(source: http://www.saiglobal.com/assuranceservices/certification/ProductCertification/)

There are a number of certified GDDs available for installation at residential premises.

The Greywater Diversion Devices Register, which is a list of licensed greywater diversion devices maintained by NSW Health, can be accessed online at www.health.nsw.gov.au.

3.6 Sub-surface Irrigation

Greywater generated by a GDD must only be reused for sub-surface irrigation, at a depth of 100 mm or more below the surface. Distribution pipes and fittings must be at least one metre from a boundary, and delivery pipes will generally need to be underground.

The sub-surface irrigation should be installed in such a manner that it will not discharge into any watercourse or cause run-off to neighbouring properties.

The irrigation system connected to the GDD does not require installation by a licensed plumber, but must follow the manufacturer’s recommendations or design where relevant, and must meet the performance standards in Clause 75A of the Regulation (reproduced in Appendix C of these guidelines).

Irrigation systems shall not be connected to both the mains water and the greywater diversion supply.

Additional information on recommended sub-surface irrigation design, maintenance and management can be found in the greywater fact sheets listed in Appendix D.

3.7 Marking, Labelling and Signage

In accordance with the NSW Code of Practice for Plumbing and Drainage 3rd Edition 2006, the GDD and associated sub-surface irrigation system must be marked, labelled and signed.

External connections shall have signs that are marked “WARNING DO NOT DRINK” in accordance with the Australian Standard AS 1319.

All pipes or pipe sleeves and identification tapes (including those on pressurised irrigation systems) shall be coloured purple as per the Australian Standard AS 2700 and marked with the following in accordance with the Australian Standard AS 1345 “WARNING RECYCLED/RECLAIMED WATER – DO NOT DRINK” at intervals not exceeding 0.5 m.

All below ground pipes (including those used for sub-surface irrigation) shall have an identification tape, marked in accordance with the Australian/New Zealand Standard AS/NZS 3500.1 Clause 9.5.4.1, installed on top of the greywater pipeline, running longitudinally, and fastened to the pipe at not more than 3 m intervals.


3.8 Maintenance

Once a GDD is installed it is the owner’s responsibility to ensure it is maintained for the life of the installation.

GDDs and their associated sub-surface irrigation distribution systems require regular maintenance, such as cleaning and replacing of filters and periodic de-sludging of the surge tank, periodic inspection of the sub-surface distribution system, and soil condition evaluation (Table 3.1).

Table 3.1 Recommended Maintenance for Greywater Diversion Devices

GDD Component Maintenance Required Approximate Frequency

Filter Clean filter

– filter should be removed and cleaned, removing physical contaminants (sand, lint, hair, etc.)

Weekly

Replace filter As recommended by the manufacturer or as required (usually every 6 – 12 months)

Surge tank Clean out sludge from surge tank Every 6 months

Sub-surface irrigation distribution system

Check that water is dispersing

– regularly monitor soil to ensure all areas are wet after an irrigation period.

Weekly

Soil condition Check that soil is healthy. Signs of unhealthy soil include:

– damp and boggy ground hours after irrigation

– surface ponding and run-off of irrigated water

– poor vegetation growth– unusual odours– clumping of soil– fine sheet of clay covering surface

Monthly

Sensor probe (if applicable) Clean level sensor to ensure correct readings and subsequently pump operation

Weekly

This maintenance work itself has inherent health risks, just like managing a worm farm or compost bin. Rubber gloves and a mask should be worn and thorough washing of hands and clothes should take place immediately afterwards.


3.9 Responsibilities

Table 3.2 Responsibilities for Greywater Diversion Devices

Action

Responsibility

Owner Plumber Other

Evaluate conditions for exemption from the prior approval by council and ensure overall compliance

Undertake a water balance to determine water demand requirements

Check with the local water utility that the property is serviced by a meter with an integral dual check valve to ensure backflow protection of the water supply

Engage a licensed plumber to install the GDD and associated non-storage surge attenuation

Ensure GDD and non-storage surge attenuation meets the requirements of the NSW Code of Practice: Plumbing and Drainage 3rd Edition 2006

Install sub-surface irrigation system to distribute greywater

Notify the local water utility that a GDD has been installed at the property

Undertake regular maintenance of the GDD in accordance with the manufacturer’s recommendations and these guidelines

3.10 Offences and Penalties

There is an onus of responsibility on the owner of residential premises where a greywater diversion device (GDD) is installed to ensure that the GDD is maintained and does not compromise public health or the environment.

The best practice management control measures identified in this guideline provide guidance on how to maintain and operate a GDD correctly, to protect public health and the environment. If the owners of premises comply in full with these guidelines, then they are exempt from council approval. If a person carries out the activity of greywater diversion without council approval and does not comply with the requirements in the Regulation, the NSW Code of Practice, and these guidelines, the exemption from approval is invalid. Under s. 626(3) of the Local Government Act 1993, the maximum penalty for carrying out an activity without prior council approval is $2200 or council can issue an on the spot fine of $220.

If a neighbour or member of the public reports a nuisance or greywater crossing boundary lines with the potential to cause a public health or environmental impact, council has the ability to follow up the complaint and issue fines or directions.

PART CADVISORY INFORMATION ON THE REUSE OF GREYWATER

Section 4 – Greywater Treatment Systems

Section 5 – Manual Bucketing of Greywater


4 GREYWATER TREATMENT SYSTEMS

4.1 Overview

A greywater treatment system (GTS) collects, stores, treats, and may disinfect, greywater to the standards specified in the NSW Health Domestic Greywater Treatment Systems Accreditation Guidelines (February 2005). They can be installed in residential premises to provide treated greywater for reuse for irrigation (including surface irrigation), toilet flushing and washing machine use.

Appendix A outlines the process for choosing and installing a greywater treatment system.

4.2 Accreditation

NSW Health is responsible for administering the requirements of Clause 41 of the Local Government (General) Regulation 2005 in accrediting GTSs and circulating accreditation notices to Public Health Units and councils.

GTSs are accredited by the Director-General of the Department of Health (NSW Health) following the process and standards specified in the Domestic Greywater Treatment Systems Accreditation Guidelines (February 2005).

A council must not approve the installation of a GTS, unless the GTS has been accredited by NSW Health. There are some instances where a GTS may be exempt from accreditation by the Director-General of the NSW Health Department. The criteria for exemption are explained on the NSW Health web page at www.health.nsw.gov.au.

The irrigation system associated with the GTS does not require accreditation by NSW Health but requires prior approval of the council.

4.3 Approvals

A GTS is defined as a waste treatment device and therefore the owner of the premises must obtain prior approval from the council for installation, and operation, under Item C5 and C6 of Section 68 of the Local Government Act 1993 and Part 2, Division 4 Local Government (General) Regulation 2005. There are no exemptions to this requirement. A council must not approve the installation of a GTS unless they have been accredited by the NSW Department of Health (Clause 41(1) of the Local Government (General) Regulation 2005).

Council may grant approval to install a GTS at a particular site in accordance with Item C5, Section 68, Local Government Act, 1993. A GTS and the associated reuse distribution system/s (e.g. irrigation system, reticulation for toilet flushing) also require approval to operate from council in accordance with Item C6 of Section 68.

It is the responsibility of the owner of the premises to engage a licensed plumber to install the GTS and to make any associated plumbing modifications (e.g. pipe for toilet flushing).

It is the responsibility of the installing licensed plumber to install the GTS to meet the requirements of the NSW Code of Practice: Plumbing and Drainage 3rd Edition 2006. The plumber must ensure that controls to prevent the incidence of cross-connection in addition to overflow and backflow protection (in the form of a backflow containment device) are implemented and that the local water utility is notified in writing that a GTS is in place at the premises. Written notification shall be in the form of “as completed plans” (e.g. an amended sewer service diagram) or other documentation as required by the local water utility.

Where a GTS is connected to internal fixtures for toilet flushing and washing machine use, a back-up water supply will be required to ensure a constant water supply to all fixtures should the GTS fail.


It is important that greywater treatment is undertaken sensibly to ensure that public health and the environment are protected. The control measures, presented here as a list of ‘Dos and Don’ts’, have been compiled to provide owners and residents with a guideline of how to best manage their reuse of treated greywater and ensuring the reuse of greywater achieves the performance standards required by the approval granted by council. Each of these control measures is explained in further detail in Appendix C of these guidelines.


These are minimum requirements for greywater treatment systems, council may have other requirements and conditions when the approval is given.

When reusing greywater treated by a greywater treatment system, DO:

DO get council approval and install a greywater treatment system (GTS) that has been accredited by NSW Health.

DO reuse treated greywater (from a GTS) only for irrigation (including surface irrigation), toilet flushing and washing machine use.

DO undertake a water balance before installing a GTS to calculate the amount of water that can be reused by the household.


DO select washing detergents that are low in salt – consider using a powder concentrate, or a liquid washing detergent.


DO occasionally irrigate with drinking water to disperse salts from the soil (only appropriate during extended periods of zero rainfall).


DO ensure that regular maintenance of the greywater system is undertaken.

DO mark and label all pipes and use signs to indicate greywater reuse (see section 4.6).

When reusing greywater treated by a greywater treatment system, DON’T:

DON’T irrigate with greywater during rain.


DON’T reuse greywater generated by washing rags used for painting or for maintaining machinery.


DON’T over-water.

DON’T reuse greywater on plants that will be eaten raw or where fruit has fallen to the ground.



DON’T install drippers of an irrigation system within one metre of boundary lines, inground pools, and inground potable water tanks and buildings.



4.5 Greywater Reuse Estimations

To estimate a household’s greywater requirements a water balance can be undertaken to consider both the amount of greywater that has the potential to be reused, and the amount of greywater that can be generated to meet the needs of the household. This is important because a typical metropolitan household can potentially generate much more water than is needed for use by the household.

All of the information and calculations to undertake a water balance are provided in Appendix B: Greywater Reuse Estimation. Appendix C provides guidance for managing greywater to protect public health and the environment.

4.6 Marking, Labelling and Signage

The marking, labelling and signage of the GTS and associated sub-surface irrigation system must be in accordance with the NSW Code of Practice for Plumbing and Drainage 3rd Edition 2006.

Greywater outlets (connections, taps, appliances) shall have signs that are marked “WARNING DO NOT DRINK” in accordance with the Australian Standard AS 1319.

All pipes or pipe sleeves and identification tapes (including those on pressurised irrigation systems) shall be coloured purple as per the Australian Standard AS 2700 and marked with the following in accordance with the Australian Standard AS 1345 “WARNING RECYCLED/RECLAIMED WATER – DO NOT DRINK” at intervals not exceeding 0.5 metres.

All below ground pipes (including those used for sub-surface irrigation) shall have an identification tape, marked in accordance with the Australian/New Zealand Standard AS/NZS 3500.1 Clause 9.5.4.1, installed on top of the greywater pipeline, running longitudinally, and fastened to the pipe at not more than 3 m intervals.

4.7 Irrigation

The irrigation system connected to the GTS does not require installation by a licensed plumber, but must follow the manufacturer’s recommendations or design where relevant.

Irrigation systems shall not be connected to both the mains water and the greywater treatment system supply.

Greywater generated by a GTS may be reused for surface or sub-surface irrigation. Distribution pipes and fittings must be at least 1 metre from a boundary, inground pool or inground potable water tank, and pipes will generally need to be underground.

4.8 Maintenance

Once a GTS is installed it is the owner’s responsibility to ensure it is maintained for the life of the installation.

The maintenance procedures provided by the manufacturer, and any conditions of approval from the council, must be carried out as specified.

The NSW Health issued certificate of accreditation for the greywater treatment system may also include specific maintenance requirements for the system.


4.9 Responsibilities

Table 4.1 Responsibilities for Greywater Treatment Systems

Action

Responsibility

Owner Plumber Other

Undertake a water balance to determine water demand requirements

Ensure GTS meets the requirements of the NSW Code of Practice: Plumbing and Drainage 3rd Edition 2006

Apply for and obtain approval to install and approval to operate the GTS and associated irrigation from the local council

Engage a licensed plumber to install the GTS

Install sub-soil, sub-surface or surface irrigation system to distribute greywater

Notify the local water utility that a GTS has been installed at the property

Undertake regular maintenance of the GTS in accordance with the manufacturer’s recommendations and these guidelines

Undertake annual testing of backflow protection device a

a It is the responsibility of the owner to organise annual testing of the backflow protection device by an accredited tester

4.10 Offences and Penalties

There is an onus of responsibility on the owner of residential premises where a greywater treatment system (GTS) is installed, to ensure that council has approved the installation and the operation of the system and that it is maintained and does not compromise public health or the environment.

Failure to obtain approval from council for the installation of a greywater treatment system, as well as failure to obtain approval to operate a greywater treatment system, are offences under section 626(3) of the Local Government Act 1993. The maximum penalty is $2200.

Councils can issue an on the spot fine of $330 for operating a greywater treatment system without approval. Failure to comply with the conditions of approval issued by council is also an offence under section 627(3) of the Local Government Act 1993. The maximum penalty is $2200. Councils can issue an on the spot fine of $330 for failing to comply with the conditions of approval for operating a greywater treatment system.


5 MANUAL BUCKETING OF GREYWATER

This section outlines the conditions of approval and the ‘Dos and Don’ts’ for manual bucketing of greywater at residential premises in sewered areas of NSW.

5.1 Overview

Manually irrigating with greywater using a bucket (e.g. collecting shower and laundry water for reuse) can reuse small quantities of greywater, potentially saving drinking water.

Bucketed greywater can be reused for irrigation of gardens, lawns and outdoor pot plants.

Manual bucketing is considered to be a low risk activity for the following reasons:

Manual bucketing reuses low volumes of greywater. Accordingly, only low quantities of contaminants will be applied to the soil and there is a limited ability for runoff to neighbouring properties or waterways.

It is unlikely that manual bucketing will occur during wet weather, reducing the risk of over-watering or runoff.

5.2 Conditions of Approval

Manual bucketing for residential premises in sewered areas of NSW does not require prior approval from council.


It is important that manual bucketing is undertaken sensibly to ensure that public health and the environment are protected. The following best practice management control measures, presented in a list of ‘Dos and Don’ts’, have been compiled to provide owners and residents with a guideline of how to best manage their reuse of greywater by manual bucketing. Each of these control measures is explained in further detail in Appendix C of these Guidelines.

The best practice management control measures (Dos and Don’ts) for manual bucketing are a necessity as they reduce the risks associated with reuse, whilst providing a water source that has the potential to improve the health and appearance of soil and plants.

When undertaking manual bucketing of greywater, DO:

DO be careful lifting and carrying buckets of greywater, particularly over slippery surfaces and on stairs or steps.


DO select washing detergents that are low in salt – consider using a powder concentrate, or a liquid washing detergent.

DO reuse greywater in the garden in several locations.



DO wash your hands after reusing greywater.


When undertaking manual bucketing of greywater, DON’T:

DON’T reuse toilet or kitchen wastewater.

DON’T reuse greywater for irrigation during rain.

DON’T apply greywater in areas that are readily accessible to children, people with a low immune system or pets.

DON’T reuse greywater generated from the washing of nappies or soiled clothing.

DON’T reuse greywater when a resident is sick, e.g. has diarrhoea.


DON’T reuse greywater generated by washing rags used for painting or for maintaining machinery and vehicles.


DON’T store untreated greywater.

DON’T over-water.

DON’T reuse greywater on plants that will be eaten raw or where fruit has fallen to the ground and could be eaten.





GLOSSARY OF TERMS

aquifer A porous soil or rock formation which holds water.

council Statutory corporation constituted under the Local Government Act 1993 for an area of NSW.

drinking water Water suitable for human consumption, used for drinking, food preparation, personal hygiene, and the removal of human wastes.

dual reticulation Two separate and distinct piping systems, one of which is used to transport drinking water, and the other for non-potable water for final uses that do not require drinking water.

fixture trap U-shaped pipe below plumbing fixtures that provides a water seal to prevent sewer odours and gases from entering habitable areas.

greywater For the purposes of these guidelines, means wastewater from washing machines, laundry tubs, showers, hand basins and baths, but does not include wastewater from a kitchen, toilet, urinal or bidet.

greywater diversion The installation and operation of a method for diverting untreated greywater generated by a household to sub-surface irrigation of a garden or lawn at that same premises.

greywater diversion device (GDD) A device that diverts greywater generated by a household for sub-surface irrigation reuse.

greywater treatment system (GTS) A system that collects, treats, and disinfects greywater generated by a household, for reuse for one or more of the following end uses: toilet and urinal flushing; washing machine; and surface or sub-surface irrigation.

groundwater Water beneath the surface held in, or moving through, saturated layers of soil, sediment or rock.

local water authority The organisation, agency or company that has responsibility and authority for treating and/or supplying water and wastewater services to a local government area.

non-potable water Water suitable for purposes other than drinking water use.

non-storage surge attenuation Allows the temporary containment of greywater to be released to an irrigation system at a constant rate via gravity or pump.

Methods of non-storage surge attenuation include: a non-storage surge attenuation tank; attenuation incorporated into the GDD system itself; or a mulch pit.

nutrients Chemical elements essential for sustained plant or animal growth. The major nutrients essential for plant growth are nitrogen, phosphorus and potassium.

pathogen Organism that is capable of causing disease in humans and animals.

percolation The descent of water through the soil.

residential premises A single household in a sewered residential area; does not include a premises comprising more than one dwelling.


GLOSSARY OF TERMS continued

reticulation A network of water pipes, which delivers water supply to customers.

risk The likelihood of a hazard causing harm in exposed populations in a specified timeframe, including the magnitude of that harm (EPHC-NRMMC, 2005).

salinity (irrigation salinity) The increasing build-up of salts in irrigated soils. It results from raised water table levels that bring soil salts into the upper levels of the soil profile.

sewage management facility A human waste storage facility or a waste treatment device intended to process sewage. Also includes a drain connected to such a facility or device. As defined in Section 68A of the Local Government Act 1993.

sub-surface irrigation Irrigation at a depth of at least 100 mm below surface level of soil or mulch.

surface irrigation Water applied to the ground surface from above surface level.

surface water All water naturally open to the atmosphere (e.g. rivers, streams, lakes and reservoirs).

surge attenuation A tank or similar to cope with sudden influxes of greywater (e.g. from a washing machine cycle) for distribution to a land application system.

thermotolerant coliforms An indicator of microbiological quality. A type of micro-organism which typically grows in the intestine of warm-blooded animals (including humans) and are shed in their millions in each gram of faeces.

wastewater Water that has been contaminated by some activity. Includes greywater and sewage.


REFERENCES

Christova-Boal, D., Eden, R. E. and McFarlane, S. (1996). ‘An investigation into greywater use for urban residential properties’. Desalination 106 (1996) 391-397.

DEC NSW (2004). Environmental Guidelines: Use of wastewater by irrigation. NSW Department of Environment and Conservation. Sydney, Australia.

Jeppesen, B. and Solley, D. (1994). Domestic greywater reuse: Overseas practice and its applicability to Australia. Research Report No. 73. Urban Water Research Association of Australia. Brisbane, Australia.

Loh, M. and Coghlan, P. (2003). Domestic water use study: In Perth, Western Australia 1998-2001. Water Corporation. Perth, Australia.

NSW Health (2005). Domestic Greywater Treatment Systems Accreditation Guidelines February 2005. NSW Department of Health. Sydney, Australia.

NSW Health (2000). Greywater reuse in sewered single domestic premises. April 2000. NSW Department of Health. Sydney, Australia.

Patterson, R.A. (2006). Consideration of soil sodicity when assessing land application of wastewater or greywater. Septic Safe Environmental Health and Protection Guidelines. Technical Sheet Reference 01/7. Department of Local Government and Lanfax Laboratories.

Sydney Water Corporation (2005). Water Conservation & Recycling Implementation Report 2004-2005. Sydney Water Corporation. Sydney, Australia.

BIBLIOGRAPHY

ACT Government (2004). Greywater Use: Guidelines for residential properties in Canberra. ACT Government. Canberra, Australia.

Australian Standards. AS 1319-1994 Safety signs for the occupational environment.

Australian Standards. AS 2700 AS 2700-1996 Colour Standards for general purposes.

Australian Standards. AS/NZS 3500.1:2003 Plumbing and drainage – Water services

Committee on Uniformity of Plumbing and Drainage Regulation in NSW (2006). New South Wales Code of Practice Plumbing and Drainage 3rd Edition. Department of Energy Utilities and Sustainability. Sydney, New South Wales.

Local Government Act 1993 (NSW)

Local Government (General) Regulation 2005 (NSW)

NSW Government (1998). Environment & Health Protection Guidelines: On-site and Decentralised Sewage Management. NSW Government. Sydney, Australia.

Patterson, R.A. (2006). Consideration of soil sodicity when assessing land application of wastewater. Septic Safe Technical Sheet 01/7. Department of Local Government and Lanfax Laboratories. Armidale, Australia.

Protection of the Environment Operations Act 1997 (NSW)

SAI Global Assurance Services. Australian Technical Specification 5200.460 – 2005.

Shaw, R.J. (1999). Soil Salinity – Electrical Conductivity and Chloride in Soil Analysis: an interpretation manual. Edited by Peverill, K.I., Sparrow, L.A. and Reuter, D.J. CSIRO. Canberra, Australia.

Water Corporation, Department of Environment (WA) and Department of Health (WA) (2005). Code of Practice for the Reuse of Greywater in Western Australia. Water Corporation. Perth, Western Australia.

APPENDICES

Appendix A Greywater Decision Flow Charts

Appendix B Greywater Reuse Estimations

Appendix C Management of Greywater

Appendix D Fact Sheets


APPENDIX A – GREYWATER DECISION FLOW CHARTS

Process Flow Chart

Do you have an on-site sewage management facility e.g. septic tank?

Is your property serviced by a dual reticulation system?

I would like to re-use greywater for:

Watering my garden using sub surface irrigation. You will need to install a Greywater Diversion Device.

GO TO CHART (1)

Watering my garden using surface irrigation, flushing my toilet and/or in my clothes washing machine

You will need to install a Greywater Treatment System. GO TO CHART (2)

Greywater reuse may not be appropriate on your property.*

You are not able to re-use greywater on your property.

NO

NO

YES

YES

* The removal of the greywater stream from the on-site sewage management facility has the potential to adversely impact on the proper operation of

the facility. You will need to ensure that your system is able to cope with the separation of the greywater before reusing greywater at your property.



Chart 1 Greywater Diversion Device

Are you in a registered environmentally sensitive area? www.dwe.nsw.gov.au

Calculate the amount of greywater you are likely to re-use. Appendix B1

Calculate the amount of greywater you are likely to generate. Appendix B2

Complete self assessment of greywater use and generation. Appendix B3

Is your property serviced by a meter with an integral dual check valve.

Select greywater diversion device. Fact Sheet 2

Engage a licensed plumber to install the GDD and associated surge attenuation.

Install sub-surface irrigation system to distribute greywater. Fact Sheet 3

Undertake regular maintenance of the GDD. Fact Sheet 5

You are not exempt from Council approval. You must apply to Council to reuse greywater on your property.

Apply to have meter with an integral dual check valve installed by your

water utility.

Meter with an integral dual check valve installed?

You are not able to re-use greywater on your property.

NO

YES

NO

NOYES

YES



Chart 2 Greywater Treatment System

Calculate the amount of greywater you are likely to re-use. Appendix B1

Calculate the amount of greywater you are likely to generate. Appendix B2

Complete self assessment of greywater use and generation. Appendix B3

Select greywater treatment system. Fact Sheet 2

Apply for and obtain council approval to install and operate the GTS.

Engage a licensed plumber to install the GTS.

Install sub-surface irrigation system to distribute greywater. Fact Sheet 3

Undertake regular maintenance of the GTS. Fact Sheet 5


APPENDIX B – GREYWATER REUSE ESTIMATIONS

To estimate a premises’ greywater requirements, a water balance can be undertaken to consider both the amount of greywater that has the potential to be reused, and the amount of greywater that can be generated to meet the needs of the premises. By undertaking a water balance owners can identify:

how they can most appropriately reuse greywater on their premises;

how to calculate how much greywater they have the potential to reuse;

how to calculate how much greywater can be generated; and

the nutrient balance of their premises.

It is essential that owners and residents complete the water balance when they plan to install a GDD. The ‘water for life’ site also provides guidance for managing greywater to protect public health and the environment.

B1 Potential for Reuse

To determine the potential of a household to reuse greywater, the end uses of greywater need to be identified. There are several end uses available for greywater reuse, depending on the reuse method and level of treatment (Table B1).

Table B1 Greywater Reuse Methods and Applications

Reuse Method Greywater Reuse Application

Manual bucketing • Limitedirrigation

Greywater diversion device (GDD) • Sub-surfaceirrigation(atleast100mmbelowsurface)

Greywater treatment system (GTS) • Surfaceorsub-surfaceirrigation

• Toiletflushing

• Washingmachine

The potential amount of greywater that can be reused for residential premises can be estimated by considering the irrigation potential of the premises.

Irrigation

The method described in this section can be used for estimating the potential amount of greywater that can be used for sub-surface irrigation (GDD or GTS greywater) or surface irrigation (greywater treated by a GTS only).

To estimate the amount of greywater that can be reused for irrigation, a number of factors need to be considered including the soil irrigation rate, size of the area to be irrigated and seasonal variations in irrigation requirements.

The irrigation volume is the amount of water that the soil can absorb per square metre of garden or lawn that will be irrigated. The irrigation volume adopted for NSW is 20 L/m2* for each event (equivalent to 20 mm/m2 of rainfall). The frequency of an irrigation volume is dependant on the soil’s capacity to hold water; this will be considered later in the estimations.

The sub-surface irrigation area can be calculated by determining the total size of all of the garden beds or lawn area that will be served by the irrigation system. The sub-surface irrigation area can then be multiplied with the irrigation volume to determine the total volume of greywater that can be reused per irrigation event. A number of example volumes have been calculated and are presented in Table B2.

* This is based on the design irrigation rate for poorly drained light clays (AS/NZS 1547:2000). It is considered to be conservative for most soils and may

be adjusted according to the health of the plants and soils at the site.


Table B2 Examples of the Volume of Greywater Reused per Irrigation Event

Volume of Greywater Reused per Irrigation Event (L)

1 m2 5 m2 10 m2 25 m2 50 m2

20 100 200 500 1000

It is important that GDDs are only turned on when the garden needs watering. Leaving a GDD turned on at all times has the potential to lead to over-watering. Just as a resident would not leave a drinking water tap turned on watering the garden at all times, the GDD should be used as a tap that is typically turned off (diverted to sewer). When the tap is turned on it is to meet the needs of the irrigation event determined above (from Table B2). Similarly, treated greywater produced by a GTS should not be continuously supplied for irrigation, and should only be used when irrigation is required.

The frequency of an irrigation event is dependant on the season. During the summer months plants require irrigation more frequently than in the winter months. The recommended frequency of irrigation events for the year is provided in Table B3.

Table B3 Recommended Seasonal Irrigation Frequency

Location – NSW Frequency of irrigation event

Summer Autumn Winter Spring

Coastal Region Every 7 days Every 13 days Every 20 days Every 9 days

Inland – East of the Great Dividing Range

Every 5 days Every 8 days Every 12 days Every 7 days

Inland – West of the Great Dividing Range

Every 4 days Every 10 days Every 14 days Every 6 days

Rainfall must also be considered as an irrigation event. For every 1 mm of rainfall, owners and residents need to adjust their irrigation volume by 1 litre per square metre (1 L/m2). So if in the first week of January there is a rainfall event of 20 mm in a coastal area, there will be no need to irrigate with greywater (or any other water source) for seven days.

Toilet Flushing

The method described in this section can be used for estimating the potential amount of greywater that can be used for toilet flushing. Only greywater treated by a GTS can be used for toilet flushing.

To estimate the amount of greywater that can potentially be reused for toilet flushing in the premises, the number of residents and the type of toilet/s installed at the premises needs to be determined.

Toilets are either full flush (one button) or dual flush (two buttons). Full flush toilets use 11 litres per flush, and dual flush toilets use 3.0 litres for a half flush and 5.5 litres per full flush on average. The calculation below assumes a ratio of four half flushes to every one full flush (AS 1172.2-1999; AS/NZS 6400:2005). Table B4 can be used to estimate the amount of water used at the premises for toilet flushing, and therefore the potential for reuse by replacing drinking water with greywater for toilet flushing.

Table B4 Potential for Greywater Reuse – Toilet Flushing

Number of residentsPotential for Reuse – Toilet Flushing (L/week)

Full Flush Dual Flush

1 308 101

2 616 202

3 924 302

4 1232 403

5 1540 504

6 1848 605

7 2156 706


Washing Machine

The method described in this section can be used for estimating the potential amount of greywater that can be used in washing machines. Only greywater treated by a GTS can be used in washing machines.

To estimate the amount of greywater that can potentially be used by the washing machine, the number of residents (or the number of washes per week) and the type of washing machine needs to be determined.

Washing machines can be front loading or top loading and can be small (up to 5.5 kg), medium (6 – 7 kg), or large (over 7.5 kg). In general, front loading washing machines are more water-efficient than top loading washing machines, based on washing machines available for domestic use over the last five years. The average front loading washing machines are medium in size and have a 4-Star rating under the Water Efficiency Labelling and Standards (WELS) Scheme. The average top loading washing machines are large in size and have a 2-Star rating under the Water Efficiency Labelling and Standards (WELS) Scheme. The size of the washing machine can be found in the manufacturer’s user manual or written on the machine itself. Alternatively, owners and residents can assume that a front loading washing machine is medium in size and a top loading washing machine is large.

Table B5 can be used to estimate the amount of water used by a washing machine per week. The number of residents or the number of washes per week can be matched with the type of washing machine, to give the estimated amount of greywater that can be reused by the washing machine.

Table B5 Potential for Greywater Reuse – Washing Machines

Number of residents

Number of washes per week

Potential for Reuse – Washing Machine (L/week)

Front Loading Washing Machine Top Loading Washing Machine

Small (up to 5.5 kg)

Medium (6 – 7 kg)

Large (over 7.5 kg)


Medium (6 – 7 kg)

Large (over 7.5 kg)

1 2 103 133 164 210 273 336

2 3 154 200 246 315 410 504

3 4 205 267 328 420 546 672

4 6 308 400 492 630 819 1008

5 7 359 466 574 735 956 1176

6 8 410 533 656 840 1092 1344

7 9 461 600 738 945 1229 1512

Assumptions: Top loading: average machine is large (over 7.5 kg) with a 2-Star WELS rating. Front loading: average machine is medium (6 - 7 kg) with a 4-Star WELS rating. Sources: AS/NZS 6400:2005; Choice Magazine 2003

B2 Greywater Generation

The potential water usage volume for a greywater generating appliance is equivalent to the volume of greywater generated by an appliance.

The data in Table 2.1 (Section 2.1.1) can be used to calculate the amount of greywater you can generate from your bathroom, laundry or both, depending on how many people live in the house.

It is appropriate to use the data in Table 2.1. However, as has been previously discussed, there is a high amount of variability associated with the generation of greywater. The figures for residential premises water use given in Section 2.1.1 in Table 2.1 are average values and may not represent a particular premises’ water usage accurately. To best estimate the amount of greywater generated by a household, it is most accurate to determine the potential for greywater generation by the household appliances at individual residential premises.


The household fixtures or appliances that can potentially be used to generate greywater are:

Shower

Bath

Basin taps

Washing machine

Laundry taps.

Shower

To estimate the amount of greywater that is generated by the shower, the number of residents at the premises and the type of shower head installed in the house need to be determined.

Shower heads are given a rating of 1-Star to 6-Stars under the Water Efficiency Labelling and Standards (WELS) Scheme depending on the amount of water they use. Only 1-Star to 3-Star shower heads are currently available. For those owners and residents that are unsure of the type of shower head they have installed, Table B6 provides a general explanation.

Table B6 Shower Head WELS Star Rating and Water Use

Installation Date Shower Head Star Rating (WELS) Water Flow (L/min)

As part of WaterFix (Sydney Water) or a similar water efficiency program

3-Star 9

Within the last 15 years 2-Star 12

More than 15 years ago 1-Star 16

Source: AS/NZS 6400:2005

Once the number of residents and the shower head type is known, using Table B7 the amount of greywater generated by the premises’ shower(s) can be determined by matching the number of residents row with the shower head type column. It is assumed that the average shower length is seven minutes (Loh and Coughlan, 2003) and that every resident has one shower per day.

Table B7 Greywater Generation – Shower (and Bath)

Number of Residents

Greywater Generation – Shower (and Bath) (L/week)

Shower Head

1-Star

Shower Head

2-Star

Shower Head

3-Star

1 784 588 441

2 1568 1176 882

3 2352 1764 1323

4 3136 2352 1764

5 3920 2940 2205

6 4704 3528 2646

7 5488 4116 3087

Assumptions: Average shower: 7 minutes (Source: Loh and Coughlan, 2003). Every resident showers (or bathes) once per day (7 times/week).


Baths

The amount of greywater generated by a bath is between 60 and 300 litres depending on the size of the bath and the level that the bath is filled to. An average bath size is 260 litres when full. However, the majority of baths are for children and will be filled to between a quarter to a half of the full bath level, generating 60 to 130 litres of greywater per bath. This is the equivalent of one seven-minute shower, so the estimation for the amount of water generated by the shower can be used to estimate the amount of water generated by the bath (Table B7). Assume that each resident showers or bathes once per day (7 times/week); for children that share a bath treat them as one resident for the purposes of the bath estimation only.

Basin Taps

To estimate the amount of greywater that is generated by bathroom basin taps, the number of residents at the premises needs to be determined.

It is estimated that each person uses 4 litres of water from the bathroom hand basin per day (face washing, teeth brushing, hand washing). This assumption is used to estimate the greywater generation from basin taps in Table B8, by matching the number of residents to the amount of greywater generated.

Table B8 Greywater Generation – Basin Taps

Number of Residents Greywater Generation – Basin Taps (L/week)

1 28

2 56

3 84

4 112

5 140

6 168

7 193

Washing Machines

To estimate the amount of greywater that is generated by the use of washing machines, the number of residents at the premises (or the number of washes per week) and the type of washing machine need to be determined.

It is appropriate to reuse washing machine wastewater as greywater in both diversion systems and greywater treatment.

Washing machines can be front loading or top loading and can be small (up to 5.5 kg), medium (6 – 7 kg), or large (over 7.5 kg). In general, front loading washing machines are more water efficient than top loading washing machines, based on washing machines available for domestic use over the last five years (Choice Magazine, 2003). The average front loading washing machines are medium in size and have a 4-Star rating under the Water Efficiency Labelling and Standards (WELS) Scheme. The average top loading washing machines are large in size and have a 2-Star rating under the WELS Scheme. The size of the washing machine can be found in the manufacturer’s user manual or written on the machine itself; alternatively owners and residents can assume that a front loading washing machine is medium in size and a top loading washing machine is large.

Table B9 can be used to estimate the amount of water generated by a washing machine per week. The number of residents or the number of washes per week can be matched with the type of washing machine, to give the estimated greywater generated by the washing machine.


Table B9 Greywater Generation – Washing Machines

Number of residents

Number of washes per week

Greywater Generation – Washing Machine (L/week)

Front Loading Washing Machine Top Loading Washing Machine


Medium (6 – 7 kg)

Large (over 7.5 kg)


Medium (6 – 7 kg)

Large (over 7.5 kg)

1 2 103 133 164 210 273 336

2 3 154 200 246 315 410 504

3 4 205 267 328 420 546 672

4 6 308 400 492 630 819 1008

5 7 359 466 574 735 956 1176

6 8 410 533 656 840 1092 1344

7 9 461 600 738 945 1229 1512

Assumptions: Top loading: average machine is large (over 7.5 kg) with a 2-Star WELS rating Front loading: average machine is medium (6 - 7 kg) with a 4-Star WELS rating.

Sources: AS/NZS 6400:2005; Choice Magazine, 2003

Laundry Taps

Laundry taps are generally used for soaking clothes and hand washing delicates.

Water that has been used to wash nappies or soiled clothing must not be diverted as greywater due to the high pathogen load of the wastewater generated.

It is estimated that a residential premises with three or less residents uses the equivalent of half a laundry tub of water per week (an average laundry tub has a capacity full to the brim of 50 litres), and a residential premises with four or more residents uses the equivalent of one full laundry tub of water per week.

The amount of greywater generated by premises from laundry taps has been estimated in Table B10.

Table B10 Greywater Generation – Laundry Taps

Number of Residents Greywater Generation – Basin Taps (L/week)

3 or less 25

4 or more 50

Assumptions: An average laundry tub has a capacity (full to the brim) of 50 litres

B3 Water Balance

The total volume of greywater that has the potential to be reused (Section 4.4.1) can be compared with the total amount of greywater that can be generated to meet the needs of the premises (Section 4.4.2) to determine the water balance for the premises.

A water balance will allow the owner or resident to determine whether they generate enough greywater to supply their potential demand, whether one source (e.g. only the shower or only the washing machine) of greywater is sufficient to meet their needs, or whether they will need both greywater and drinking water to fulfil their demand.

The easiest way for owners or residents to determine their water balance is to write the volume of water that can potentially be reused and generated by the premises in a table form (similar to the Table in the example below), so that all volumes are clearly identified.


Example Water Balance – Greywater Diversion Device

The Smith family of four live in sewered residential premises and want to use greywater for irrigating the gardens in their backyard.

The Smith family can use a greywater diversion device (GDD) to divert greywater for sub-surface irrigation only, without prior approval from council, providing they meet the self-assessable conditions and follow the control measures for reusing greywater safely stated in these guidelines.

Garden size: Two garden beds, both 2.5 m x 5 m (12.5 m2) in size, so a total area of 25 m2

Number of residents: 4

Potential for Reuse

Irrigation potential From Table B2, with 25 m2 irrigation area, there is potential to reuse 500 litres per reuse volume: irrigation event

Greywater Generation

Shower and bath: The shower head was installed less than 15 years ago; from Table B6, shower head has a 2-Star rating

From Table B7, with 4 residents the premises generates 2,352 litres per week

Basin taps: From Table B8, with 4 residents the premises generates 112 litres per week

Washing machines: Medium sized top loading washing machine

From Table B9, with 4 residents the premises generates 819 litres per week

Laundry taps: From table B10, with 4 residents the premises generates 50 litres per week

Water Balance

Use / Appliance Potential for Reuse (L/week) Greywater Generated (L/week)

Irrigation 500

Shower and bath 2,352

Basin taps 112

Washing machine 819

Laundry taps 50

Total 500 3,333

Water Balance = Total Greywater Generated – Total Potential for Reuse

Water Balance = 3,333 – 500 = 2,833 L/week

The water balance for greywater at the premises can be determined by deducting the total greywater requirement from the total greywater generated:

Total Greywater Generated – Total Greywater Requirement = Water Balance

From the previous examples and the Table: 3,333 – 500 = 2,833 L/week

The Table also allows an easy understanding of where greywater could be generated to meet the requirements of one or more end uses. In this household the total greywater generation is well in excess of the needs.

For example, the volume of greywater generated by the washing machine could be used to meet the requirements for irrigation over one week. However, considering the shower generating 2,833 litres per week of greywater, or the equivalent of 405 litres per day, the irrigation event demand could be met in one day of shower greywater reuse.

There is no need in this example to connect both the shower and the washing machine to a GDD. It is likely that the decision regarding which appliance to fit the GDD to would be based on which appliance allowed for the easiest access.


Example Water Balance – Greywater Treatment System

The Jones family of four live in sewered residential premises and want to use greywater for toilet flushing, their washing machine, and irrigating the gardens in their backyard.

The Jones family can use a greywater treatment system (GTS) to treat greywater generated at the premises for toilet flushing, washing machine reuse, and surface irrigation of their gardens. The Jones family must receive approval to install and operate their GTS from their local council and the GTS must be accredited by NSW Health.

Garden size: Two garden beds, both 2.5 m x 5 m (12.5 m2) in size, so a total area of 25 m2

Number of residents: 4

Potential for Reuse

Irrigation potential From Table B2, with 25 m2 irrigation area, there is potential to reuse volume: reuse 500 litres per irrigation event

Toilet flushing The Jones family have a full flush toilet; from Table B4, potential reuse volume: the toilet has the potential to reuse 1,232 litres per week

Greywater Generation

Shower and bath: The shower head was installed less than 15 years ago; from Table B6, shower head has a 2-Star rating

From Table B7, with 4 residents, generates 2,352 litres per week

Basin taps: From Table B8, with 4 residents, generates 112 litres per week

Washing machines: Medium sized top loading washing machine From Table B9, with 4 residents, generates 819 litres per week

Laundry taps: From Table B10, with 4 residents, generates 50 litres per week

Water Balance

Use / Appliance Potential for Reuse (L/week) Greywater Generated (L/week)

Irrigation 500

Toilet Flushing 1,232

Shower and bath 2,352

Basin taps 112

Washing machine 819 819

Laundry taps 50

Total 2,551 3,333

Water Balance = Total Greywater Generated – Total Potential for Reuse

Water Balance = 3,333 – 2551 = 782 L/week

The water balance for greywater at the premises can be determined by deducting the total greywater requirement from the total greywater generated:

Total Greywater Generated – Total Greywater Requirement = Water Balance

From the previous examples and the Table: 3,333 – 2,551 = 782 L/week

The Table also allows an easy understanding of where greywater could be generated to meet the requirements of one or more end uses. In this household the greywater generation exceeds their needs.

For example, the volume of grey

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